solution to 4.26

[sicp.git] / src / sicp / ex4_26.rkt

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+#lang racket
+
+#|
+
+Yes, if 'unless' were implemented in an applicative order language, then
+it would be implemented as a special form and would be translated into
+other functions before evaluation.
+
+Now, if such a special form is used in a higher order function like 'map'
+for instance:
+
+(map unless '((p-list) (usual-list) (exception-list)))
+
+then, unless gets expanded before evaluation. But map expects a function
+as its second argument.
+
+To see the implementation of unless, see metacircular2.rkt
+
+|#